HSC Biology Question Thread

[Razeen25]

Hii,

For the dot point "Compare responses of named ectothermic and endothermic organisms...", do we need to know the scientific name of each organism, or is 'Red Kangaroo' enough?

Also for "Develop a model of a feedback mechanism" is a flowchart of how the stimulus-response pathway assists temperature control in the body enough? I don't know if I'm studying less than I should be lol

Thank you!!

[Potatohater]

Hii,

For the dot point "Compare responses of named ectothermic and endothermic organisms...", do we need to know the scientific name of each organism, or is 'Red Kangaroo' enough?

Also for "Develop a model of a feedback mechanism" is a flowchart of how the stimulus-response pathway assists temperature control in the body enough? I don't know if I'm studying less than I should be lol

Thank you!!

1. Red kangaroo is enough, but just kangaroo is not. So yes, use your red kangaroos and, for ectotherms, red bellied black snakes, blue tounge lizards etc.
You have to be speciffic but not scientiffic
2. Yes that's perfect, a flow chart that explains how different tempratures trigger the stimulus-response pathway and what happens as a result, eg. Sweating, shivering etc. is exactly what they mean

[theyam]

Hi,
So basically a mutation in DNA can change cell function in this way
Mutation -> mRNA codons are altered due to changed DNA -> tRNA codons altered due to changed mRNA -> potentially different amino acids in the chain -> different polypeptide -> different protein -> different cell function
I do hope that makes sense 

Hello,
Man every time I tried searching it up, I'd see the below flow charts and I was just like ._. So thank you so much for that explanation it really helped me!

Thank you

from theyam

[Potatohater]

Hello,
Man every time I tried searching it up, I'd see the below flow charts and I was just like ._. So thank you so much for that explanation it really helped me!

Thank you

from theyam

Ahhh yes, so that diagram makes sense to me but I agree, it's not the best at explaining the concept when people havnt learnt it before. I'm glad I helped 

[Razeen25]

1. Red kangaroo is enough, but just kangaroo is not. So yes, use your red kangaroos and, for ectotherms, red bellied black snakes, blue tounge lizards etc.
You have to be speciffic but not scientiffic
2. Yes that's perfect, a flow chart that explains how different tempratures trigger the stimulus-response pathway and what happens as a result, eg. Sweating, shivering etc. is exactly what they mean

Thank you so so much!

[beeangkah]

Helllo could someone explain the reasoning to get the answer to this?

I think that at least B is definitely out as males can't be carriers, but how do I go on from there?

[PhoenixxFire]

Helllo could someone explain the reasoning to get the answer to this?

I think that at least B is definitely out as males can't be carriers, but how do I go on from there?

Hey,
So first you need to identify the mode of transmission. It must be X linked because individual 1 is not affected (he would be if it was Y linked). It also must be recessive because Individual 2 is not affected. So now you know that it is a X linked recessive trait.

This means that individual 1 cannot be a carrier (as you have already identified). Therefore individual 2 must be a carrier (otherwise their children could not have the condition).

Males cannot be carries of X linked recessive disorders as they only have 1 X chromosome so therefore Individual 3 must be normal. (Individual 3's partner would be the carrier who gave their son the condition).

Therefore the answer is C.

[beeangkah]

Could someone please explain how to get the answer for this? x

Thanks

[jasn9776]

well this is meiosis where the different sized chromosomes are homologous. (The diagram represents an organism with 4 diploid chromosomes or 2 pairs of homologous chromosomes). In reality humans have 23 pairs of chromosomes. So the homologous chromosomes meet at the middle during metaphase 1. Crossing over can occur in which segments of homologous chromosomes swap over, resulting in new combinations of alleles.

What is important to note is that the two different sides of the second cell(in the diagram) will split into two different cells.
This means that the ABAb chromosome will end up with the EDED chromosome in a separate cell after the cell divides into two.

After this they will split again and the end result is a daughter cell with two single chromatids(without the centromere connecting another one).
Remember each big chromosome e.g. AB or Ab must have a small chromosome e.g. ED or ED in each daughter cell since they are different chromosomes and the daughter cell needs a copy of each.

So really the AB can go with ED or ED but they are the same so
combo 1: ABED
combo 2:AbED
combo 3:aBed
combo 4:abed

Hope that helps. See the attachment for what the end result should look like. though it doesn't show crossing over

[BrittyG]

Hi all,

I'm having trouble with 9.4 Search for better health FQ3 where it asks to describe a named infectious disease in terms of cause, transmission etc. My class has chosen to do Malaria and I'm struggling to understand how the transmission of Malaria takes place. I was wondering if someone could lay it out in steps of what happens in the malaria transmission cycle (pretend you're explaining to a five-year-old)

Thanks in advance

[Potatohater]

Hi all,

I'm having trouble with 9.4 Search for better health FQ3 where it asks to describe a named infectious disease in terms of cause, transmission etc. My class has chosen to do Malaria and I'm struggling to understand how the transmission of Malaria takes place. I was wondering if someone could lay it out in steps of what happens in the malaria transmission cycle (pretend you're explaining to a five-year-old)

Thanks in advance

Ok so mosquitoes suck people's blood
Malaria is in persons blood
Mosquito carries malaria inside it
Mosquito sucks another person's blood
They inject a little bit of saliva as they suck the blood
Malaria goes into the new person's blood
Malaria then attacks red blood cells and reproduces in the liver
Malaria continues to attack blood cells and make person sick.
Another mosquito can then come and transfer malaria from sick person to a healthy person in the same way and the cycle continues

[BrittyG]

Ok so mosquitoes suck people's blood

Thank you so much, clears everything up

[Mate2425]

Hi i just wondering if they are any alternatives to the HSC Biology 2017 Q27a answer. The answer seems too simple.
Thanks 

[Potatohater]

Hi i just wondering if they are any alternatives to the HSC Biology 2017 Q27a answer. The answer seems too simple.
Thanks 

Ayy that was my year! Remind me, what was the question again?

[blasonduo]

Hi i just wondering if they are any alternatives to the HSC Biology 2017 Q27a answer. The answer seems too simple.
Thanks 

Hey! I agree, when those answers came out, my class was baffled at how simplistic their answer was, clearly that wasn't worth the 2 marks... right?

My answer looked like something like the attached, and I feel like that was plenty for the 2 marks.